Prediction of ice shapes on a wind turbine blade makes it possible to estimate the power production losses due to icing. Ice accretion on wind turbine blades is responsible for a significant increase in aerodynamic drag and decrease in aerodynamic lift and may even cause premature flow separation. All these events create power losses and the amount of power loss depends on the severity of icing and the turbine blade profile. The role of critical parameters such as wind speed, temperature, liquid water content on the ice shape, and size is analyzed using an ice accretion prediction methodology coupled with a blade element momentum tool. The predicted ice shapes on various airfoil profiles are validated against the available experimental and numerical data in the literature. The error in predicted rime and glime ice volumes and the maximum ice thicknesses varies between 3% and 25% in comparison with the experimental data depending on the ice type. The current study presents an efficient and accurate numerical methodology to perform an investigation for ice-induced power losses under various icing conditions on horizontal axis wind turbines. The novelty of the present work resides in a unified and coupled approach that deals with the ice accretion prediction and performance analysis of iced wind turbines. Sectional ice profiles are first predicted along the blade span, where the concurrence of both rime and glaze ice formations may be observed. The power loss is then evaluated under the varying ice profiles along the blade. It is shown that the tool developed may effectively be used in the prediction of power production losses of wind turbines at representative atmospheric icing conditions. KEYWORDS atmospheric icing, ice accretion, power losses, wind energy
INTRODUCTIONIn recent years, producing energy from renewable energy sources is in great demand and installation of wind turbines in the world has been increasing steadily. Cold climate regions have the advantage of high wind speeds, high air density, and sparsely populated residential areas.However, wind turbines in these regions are usually exposed to atmospheric icing conditions, which have a detrimental effect on the performance.Formation of ice on wind turbine blades creates unwanted performance losses by changing blade aerodynamic characteristics and also reduces the lifetime of wind turbine components. 1,2 It is well-known that icing occurs when supercooled droplets in the atmosphere impinge on a surface such as a turbine blade. Liquid water content, temperature, droplet diameter, and wind speed are the basic factors affecting icing. Liquid water content mostly determines the severity of icing and its type. Wind speed and temperature also influence the type and intensity of ice. Droplets may either freeze instantly and form rime